A miniature representation of a page or image that is used to identify a file by its contents. Clicking the thumbnail opens the file. Thumbnails are an option in file managers, such as Windows Explorer, and they are found in photo editing and graphics programs to quickly browse multiple images in a folder. In drawing programs as well as programs that deal with page layouts, thumbnails might be used to rearrange the page order by dragging and dropping them into a different sequence.
Thumbnails of Images
In Windows File Exlorer, thumbnails can be as small as this example or expanded for more detail without viewing the full-size image. The green dots indicate files the Carbonite backup service uploads up on a regular basis.